<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>

<body>
  <script>
    // function getSum(x, n) {
    //   console.log(x * n)
    // }
    // getSum(8, 9)

    function getSum(x) {
      let sum = 0
      for (let i = 1; i <= x; i++) {
        sum += i
      }
      console.log(sum)
    }
    getSum(+prompt("请输入一个数字"))
  </script>
</body>

</html>